1. Field of the Invention
The present invention relates generally to a eyeglass type image display apparatus which permits monitoring of an image, such as a video or television image, in an immediate form via a pair of ocular lenses.
2. Description of the Prior Art
Eye glass type image display devices, or `head mounted` image displays, have been disclosed, for example, in Japanese Patent Application (First Publication) 3-251667 by the present applicant. Such a conventional eye glass type image display device will be discussed hereinbelow with reference to FIGS. 34 and 35.
In the drawings, a head-mounted image display apparatus 100 has a front frame 101, comprising an essentially rectangular body portion, retained by a pair of bows 102, 102 to be held to the head of a user in a manner similar to a pair of eyeglasses. Also provided at a lower center portion of the front frame 101 are an inverted V-shaped nose pad 101a and an inverted V-shaped reflector 103. As best seen in FIG. 34, mounted at a position above the reflector 103, a fluorescent tube 104 is provided. At both sides of the reflector 103, color liquid crystal display (LCD) panels 105, 105 (image display means) are arranged. For each of the LCD panels 105, 105, a convex focus lens is formed substantially integrally therewith via deflection panels 107, 107 Mounted within the front frame 101, so as to be positioned at the inner sides of left and right eyes of user, focusing lenses 106, 106 are provided and, ocular lenses 108, 108 are mounted in a position so as to be in front of the left and right eyes of a user respectively Reflectors 109, 109, of a rectangular plate type, are arranged so as to reflect images focused through the focusing lenses 106, 106 to the ocular lenses 108, 108.
It will also be noted in FIG. 35 that earphone cups 102a, 102a are provided on each of the bows 102, 102 which may be utilized to provide sound accompaniment to images supplied to the image display means.
As seen in the explanatory diagram of FIG. 34, when such a conventional head mounted image display apparatus 100 is worn over the face of a user, images formed on the pair of LCD panels 105, 105, from a VTR or the like, are irradiated by the fluorescent tube 104 and projected in enlarged form on the retinas a, a of the left and right eyes A, A of the user, via the focusing lenses 106, 106, the reflectors 109, 109 and the ocular lenses 108, 108. The virtual image reflected on the ocular lenses are adjustable to establish a comfortable viewing distance for the user.
However, in such conventional head-mounted image display apparatus as described above, since the reflector 103 is mounted above the nose pad to assist in projecting the images displayed on the LCD panels 105, 105, to the eyes by lateral deflection, it is difficult to enlarge the nose pad portion of the apparatus such that the reflector 103 will not contact the user's nose. That is, when a user having a larger nose wears the display apparatus 100, it is difficult to match the left and right eye positions of the user with the positions of the ocular lenses 108, 108. Further, since the LCD panels 105, 105, cannot be moved closer to the reflector 103, the conventional apparatus cannot be adapted for users who have a substantially small distance between their eyes. In addition, since focusing adjustments are made by moving the respective ocular lenses 108, 108 so as to vary a distance between the eyes A, A and the ocular lenses 108, 108, it is possible that a portion of the image may `drop out`, that is to say, to be beyond the focal range of the ocular lenses 108, 108, at some positionings thereof.
Therefore, it has been required to provide a head mounted image display apparatus which is adaptable to a wide range of facial types and in which satisfactory focusing and eye distance adjustment can be easily and reliably carried out.